Đáp án+giải thích các bước giải:
a)
$B=\dfrac{2}{5}+\dfrac{3}{5}.\dfrac{25}{9}-\dfrac{5}{3}$
$= \dfrac{2}{5} +\dfrac{5}{3}-\dfrac{5}{3}$
$= \dfrac{2}{5}$
b)
$\dfrac{3}{5}.\dfrac{7}{9}+\dfrac{3}{5}.\dfrac{16}{9} - \dfrac{3}{5}.\dfrac{5}{9}$
$= \dfrac{3}{5}.(\dfrac{7}{9}+\dfrac{16}{9} - \dfrac{5}{9})$
$= \dfrac{3}{5}.2$
$= \dfrac{6}{5}$
c)
$\dfrac{5^{102}.9^{1000}}{3^{2004}.25^{50}}$
$= \dfrac{5^{102}.3^{2000}}{3^{2004}.5^{100}}$
$= \dfrac{5^2}{3^4}$
$ = \dfrac{25}{81}$
